DE19614322A1 - Procedure for receiving and evaluating RDS data streams from several transmitters - Google Patents

Abstract

The reception method uses a single receiver for reception of radio data signal (RDS) streams from a number of transmitters. the method involves tuning the receiver to one transmitter and evaluating the data streams received from the other transmitters via a RDS decoder. The receiver is re-tuned to a second transmitter for a short interval, a predetermined number of times for extraction of synchronisation information used for subsequent short-term re- tuning of the receiver to the second transmitter.

Description

The invention relates to a method for receiving and evaluating RDS Data streams from several transmitters, in addition to reception and playback of a first transmitter whose RDS data stream is evaluated and additionally the RDS data stream of other stations is evaluated.

For the reception of radio stations which, in addition to the audio signal, have an RDS Send data stream, various radio receivers are known.

With a first radio receiver there is only one receiver for that Broadcast signal and a single decoder for evaluating the RDS Data stream available. Such radio receivers are used by manufactured by the applicant and under the type designation WKC 7500 RDS expelled.

If the reception of the program on the originally set deteriorates Reception frequency, it is automatic in the known radio receiver another reception frequency is set on which the set program can also be received.  

For this purpose, the alternatives stored in a memory are used Receiving frequencies checked whether there is a transmitter of sufficient quality on them can be received. For this, the tuner of the radio receiver is briefly from the original reception frequency to the alternative reception frequencies matched and the reception properties are determined. Then will the tuner is tuned back to the original reception frequency. The Interruption is so short that it is not in the reproduced audio signal becomes audible. The band can also be checked for new stations.

After checking the alternative reception frequencies, the tuner tentatively tuned to the reception frequency for which the highest Reception level was determined to be from the RDS data stream Program information (PI code) to win and with the program information of the Compare the program on the originally set reception frequency. If a discrepancy is found, the tuner will revert to the original set reception frequency. This review is in the reproduced audio signal audible because it takes longer.

If the transmitter fails completely at the originally set reception frequency, a search is necessary in which the reception band for a station with a Program information is searched that with that of the originally set Transmitter matches. Such a search will render the Audio signal interrupted for several seconds.

In a second known radio receiver, two receivers are for Broadcast signals and two decoders for evaluating RDS data streams available. Such radio receivers are used, for example, by the company Becker manufactured and marketed under the type designation Mexico 2330.

One of the receivers and one decoder is used to receive the original set program used while the second receiver and the second Decoders are used to continuously receive the other receivable stations and evaluate the RDS data streams.  

If it is necessary to change the transmitter, use the second receiver and second decoder data can be accessed, thereby reducing the ensures smooth playback of the originally selected program is. By using a second receiver and a second decoder is the effort for the implementation of the second known radio receiver however very high.

Against the background of the known radio receivers, it is the task of present invention, a method for the reception and evaluation of Specify RDS data streams from multiple transmitters with a single receiver.

According to the invention, this object is achieved by the features of claim 1.

The advantage of the method according to the invention can be seen in the fact that Use of a radio receiver with a single receiver of the RDS Data stream of several transmitters can be evaluated, reducing the functionality and the advantages of a radio receiver with two receivers at essential less effort can be realized.

Further advantages result from the dependent claims and the following description with reference to figures.

It shows

Fig. 1, the synchronization according to the invention on the RDS data stream of a second transmitter, with a read-out time to the second transmitter, which is greater than or equal to the duration of two blocks,

Fig. 2, the synchronization according to the invention on the RDS data stream of a second transmitter, with a read-out time to the second transmitter, which is greater than or equal to the duration of a block, and

Fig. 3 shows the synchronization according to the invention on the RDS data stream of a second transmitter, with a readout time on the second transmitter, which is less than the duration of a block.

To implement the present invention, a radio receiver according to the Concept of the single-ended radio receiver described above Receiver and a single RDS decoder used.

It is essential for the applicability of the method according to the invention that the existing phase locked loop in the receiver of the radio receiver used (PLL) has a short settling time in order to tune to the to be able to make different reception frequencies as quickly as possible.

With regard to the settling time, the RDS decoder used is too consider. If the settling time of the RDS decoder used is too long , a second RDS decoder can be used, which is only for decoding of the RDS data stream of the other stations is used.

When data is transferred to RDS, the data is divided into Blocks Each block contains an information word and a check word, where in Information word containing the data to be transferred while the check word contains error protection and synchronous information for each block. Four Blocks form a group. The size and duration of the individual data elements of the RDS data stream can be found in the table below.

The four blocks of each group contain an offset Word. The offset words designate the blocks as A, B, C and D. The data content of block A always contains the program information (PI) unchanged, while the data content of blocks B, C and D can change from group to group. This is important when determining synchronous information and when evaluating the RDS Data stream of importance and will be explained in detail later.

To evaluate the RDS data streams of several transmitters, the Radio receiver that is tuned to a specific first transmitter and reproduces its audio signal, briefly gated on a second transmitter. To do this, the receiver is tuned to the receiving frequency of the second transmitter Voted. The RDS decoder uses the test words of the RDS Data stream of the second transmitter obtained synchronous information with which a Timer, e.g. B. a counter is synchronized. Then the recipient again tuned to the reception frequency of the first transmitter, its audio signal is played. Because of the synchronization by means of the timer, the point in time at which, for example, the Program information (PI), which is always contained in block A, from the second Transmitter is sent, the receiver can timely on the reception frequency of the second transmitter, so that from the RDS data stream second transmitter, the program information can be evaluated. After this Reading out the desired block or blocks, the receiver is back on the Receiving frequency of the first transmitter tuned. That way they can Program information of all receivable stations are determined and if necessary, you can move to another transmitter without an audible interruption same program content can be switched. In addition to the extraction of In principle, program information is also the acquisition of all others in the RDS Data contained information possible.

Depending on the length of the gating interval on the second transmitter, this results in various options for evaluating the RDS data stream of this transmitter.  

The length of the gating interval results from the settling times of the Phase locked loop for tuning to the second transmitter and return to the first transmitter and from the settling time of the RDS decoder.

In Fig. 1, the synchronization according to the invention on the RDS data stream is a second transmitter and evaluating the RDS data stream, is provided with a read-out time to the second transmitter, which is greater than the duration of two blocks (44 ms) is shown.

In the first evaluated group 1) of the RDS data stream of the second transmitter z. B. recognized the offset word C of the third block. For the detection of the Offset words require an entire block consisting of an information word and check word, which RDS decoder is fully available. By means of the recognized offset word C, the timer is synchronized and started. Of the The receiver is then tuned back to the first transmitter. For Evaluation of the desired program information is controlled by the receiver by the timer, so timely tuned to the second transmitter that too Start of the first block of the second evaluated group 2) of the RDS Data stream of the second transmitter all transients are finished and the RDS decoder can evaluate the information word of the first block, the Correctness is confirmed by recognizing the offset word A. Then will the receiver is tuned back to the first transmitter.

In FIG. 2, the synchronization according to the invention on the RDS data stream is a second transmitter, a block is shown having a read-out time to the second transmitter, which is greater than or equal to the duration (22 ms).

As already indicated above, the recognition of the offset words by the RDS Decoder only possible if the complete information word and the associated one Check word available together. The gating time is of the order of magnitude Problems of a group arise because of the data content of each Blocks of different groups, except for block A, which contains the program information contains, deviates from each other.  

Because of the readout time selected in this example, it is no longer possible to fully evaluate a block (information and check word). For this reason, as shown in FIG. 2, the receiver within each group is tuned to the second transmitter for the predetermined gating time.

The times of the gating are chosen so that the settling time always ends when the position in the same block as in the readout time of the last group received was ended. It is the same possible to choose the gating so that the readout times are slight overlap. In this way it is possible to have an RDS data stream assemble that has complete blocks. For this, the during the Read-out data temporarily stored, for which a memory, for. B. a shift register, which is 26 bits in size, can be used to be able to save a complete block. Because of the ones already mentioned Differences in the data in the individual blocks of different groups can this composition leads to consistent results only for block A.

In the example shown in FIG. 2, the composition of block A is only completed after six groups. The information word and part of the test word of block A come from group 5), the missing part of the test word from group 6). After the recognition of the offset word A, the synchronization described above and further evaluation of the RDS data stream are possible, the described memory for the composition of the RDS data also being used to evaluate the RDS data stream. Between the strokes on the second transmitter, the receiver is tuned to the first transmitter in order to reproduce the audio signal.

In Fig. 3, the synchronization according to the invention on the RDS data stream of a second transmitter is provided with a gated on at the second transmitter, which is less than the duration of a block (22 ms) is shown.

In this case too, the RDS data stream of the second transmitter for the individual blocks is composed of different groups, as described for FIG. 2. In the example shown, the composition of the RDS data stream for block A from group 4) and 5) takes place. A check can then be carried out in the other groups, in which block A is reassembled and evaluated. This can be prevented with sufficient certainty that a bit combination that happens to correspond to block A is used for synchronization. Between the strokes on the second transmitter, the receiver is tuned to the first transmitter in order to reproduce the audio signal.

In addition to the evaluation shown in the figures, each in succession Groups can also evaluate any groups, i.e. H. it can several groups between repeated gating on the second transmitter lie.

To the switching processes between the first and the second transmitter as possible To make it inaudible, either very short switching periods can be selected become, d. H. less than the duration of a block of 22 ms, or it will be Times used in which due to the signal properties of the reproduced audio signal of the first transmitter, the audibility is low. This can for example zero crossings of the audio signal or After masking effects (psychoacoustics). Another possibility is the Interpolation of the audio signal to be reproduced, for example by means of of an existing digital signal processor can be made or a combination of the measures described.

In the description above, only the switch between one described first and a second transmitter. Of course, the RDS Data streams of all possible reception frequencies continuously using the be evaluated according to the inventive method.

Claims (8)

1. A method for receiving and evaluating RDS data streams from several transmitters with a single receiver using an RDS decoder, the receiver being tuned to the reception and playback of a first transmitter and using its RDS decoder in addition to the RDS data stream of the first transmitter additionally evaluates the RDS data stream of further transmitters, with the following procedural steps:

• a) briefly tuning the receiver to one of the other transmitters,
• b) determining synchronous information contained in the RDS data stream of the further transmitter by means of the RDS decoder and starting a device which generates a clock synchronously with the clock of the RDS data stream of the further transmitter
• c) tuning the receiver to the first transmitter, and
• d) briefly re-tuning the receiver to the other transmitter to which the receiver was already tuned in method step a), taking into account the clock generated after method step b), for receiving and evaluating certain RDS data from the RDS data stream.

2. The method according to claim 1, characterized, that the brief tuning of the receiver to the other transmitter after Method step a) takes place for a period of time which is dimensioned such that the Switching process in the reproduced audio signal of the first transmitter in is essentially inaudible.   3. The method according to claim 1 or 2, characterized, that the brief tuning of the receiver to the other transmitter after Method step a) takes place at a time when the switching process due to the signal properties of the reproduced audio signal of the first Transmitter is essentially inaudible, especially during a Zero crossing of the audio signal. 4. The method according to any one of claims 1 to 3, characterized, that while briefly tuning the receiver to the others Transmitter after step a) the audio signal to be reproduced from the first Transmitter is simulated by signal estimation, in particular interpolation. 5. The method according to any one of claims 1 to 4 characterized, that the synchronous information determined after method step b) by repeated brief tuning of the receiver to the other transmitter, to which the recipient was already coordinated in process step a) is put together. 6. The method according to any one of claims 1 to 5, characterized, that determined after method step d) received and evaluated RDS data by briefly tuning the receiver to the further transmitter to which the receiver is already in step a) was coordinated, taking into account that generated after process step b) Clocks, to be put together.   7. The method according to any one of claims 1 to 6 characterized, that for evaluating the RDS data stream of the first transmitter and Evaluation of the RDS data stream of the other transmitter each has its own RDS decoder is used. 8. The method according to any one of claims 1 to 7 characterized, that the method in a radio receiver, in particular a Radio receiver for motor vehicles is used.